1. Field of the Invention
The present invention relates to an image measurement apparatus and an image measurement method.
2. Description of Related Art
Heretofore, there is known an image measurement apparatus that takes an image of a measurement spot of a work by a charge coupled device (CCD) camera or the like and performs edge detection or the like to the taken image (see, Japanese Patent Application Laid-Open Publication No. 08-247719, for example).
The edge detection is, for example, a technique for obtaining edge information (e.g. positional coordinates) of a subject graphic to be measured included in the taken image and measuring graphical information such as a position or a width of the subject graphic, according to an edge detection tool that is set by a user within the taken image.
As the edge detection tool, for example, a rectangular tool (referred to as a box tool, hereinafter) 73 shown in FIG. 14A and an annular-shaped tool (referred to as a circular tool, hereinafter) 74 shown in FIG. 14B are well-known.
The box tool 73 is better suited for edge detection of a linear portion 72a in the image and is defined by a position coordinate (X, Y) of a midpoint of the box tool 73, a distance W between both ends of the box tool 73 across the linear portion 72a, a width H of both sides of the box tool 73 in parallel with the linear portion 72a, and an angle θ.
In the case of the box tool 73, edge detection toward an arrowhead from a base thereof is repeatedly performed at an interval of ΔH which is preliminarily set within the width H.
The circular tool 74 is better suited for edge detection of a circular image 72b and is defined by a position coordinate (X, Y), an inside diameter r1 from which the detection starts, and an outside diameter r2 at which the detection ends.
In the case of the circular tool 74, edge detection toward an arrowhead from a base thereof is repeatedly performed with rotation centering on the coordinate (X, Y) at an interval of Δθ which is preliminarily set.
Moreover, there is known an image measurement apparatus provided with a function called “a step-and-repeat function” for continuously measuring the subject graphics to be measured, which graphics are equally spaced and regularly arranged, by setting a displacement amount of the edge detection tool and the number of measurements to be performed.
However, in such a conventional image measurement apparatus, a user by oneself has to manually set the edge detection tool within the taken image to execute the above-mentioned edge detection, thereby measuring the graphical information is troublesome.
Moreover, in the case of measuring the graphical information by using the step-and-repeat function, it is necessary to set the displacement amount of the edge detection tool that is set within the taken image and to set the number of measurements to be performed, thereby measuring the graphical information is further troublesome.